A borehole is generally drilled into an earth formation in order to extract hydrocarbons from a reservoir. The hydrocarbons may be in the form of oil and/or gas. The hydrocarbons are produced by lowering the pressure in the borehole so that the hydrocarbons, which are under higher pressure, flow into the borehole and to the surface of the earth.
If the hydrocarbons in the formation are in the form of oil and gas, it is important to know the bubble pressure of the oil. The bubble pressure relates to the highest pressure at which a chemical constituent in a liquid turns to vapor and forms bubbles. Thus, if only oil is desired to be extracted and the pressure in the borehole is lowered below the bubble point, mostly or only gas will flow out because the hydrocarbon gas has a lower viscosity than oil. Hence, in order to extract oil, it is important to extract the oil at a pressure above the bubble point. Keeping the pressure in the borehole above the bubble point but close to the bubble point will improve the rate of production since the lower the pressure the higher the rate of oil production will be. Therefore, it would be well received in the drilling industry if a downhole tool were available to accurately measure the bubble pressure of oil.